Increasingly in medicine and surgery, the need arises to place a mass of material either into body tissue or into a space in the body proximate to body tissue for various clinical purposes. These purposes include the bulking of tissue as a therapy for intrinsic sphincteric deficiency (ISD) which gives rise to incontinence. In some types of incontinence, a decrease in urethral resistance leads to urinary leakage during stress. This leakage is embarrassing, and may cause the person to change their life-style to avoid activity. Recently, various injectable materials have been suggested for the purpose of `bulking` the peri-urethral space, coapting the urethra, and thus increasing the urethral resistance.
Other clinical applications include the implantation of material include the occlusion of aneurysms, arteriovenous malformations (AVMs), and fistulas, as well as the occlusion of the blood supply to tumors, especially cranial tumors, prior to surgery to reduce bleeding during surgery.
To insure that such procedures are minimally invasive, it was clinically determined that bulking, for example, should be accomplished through needle injection. Due to the use of a needle, it was believed that it was necessary to reduce the material to a liquid suspension or particulate so that it might be capable of being passed through a needle into the tissue. This reduced the number of candidate materials significantly. Teflon (PTFE) particles, silicone particles, collagen suspensions, and various other materials were tried. Most of the problems associated with the therapy were associated with the material. For example, collagen resorbed too quickly, creating the need for many repeat therapies. Teflon particles migrate through the body and are thus clinically undesirable.
Known technology has similarly limited the materials which can be delivered transvascularly, endoscopically, or via a conduit in conjunction with a laparoscope. Articles that are delivered by pushing and utilization of these devices are limited, typically, either to fluids or to relatively stiff solids.
The controlled release of drugs from polymer and from surgical suture is another therapeutic modality known in the art. Application of this technique, however, has hitherto required the insertion of suture using conventional methods of pulling the suture into the tissue, as by means of a sewing needle or tweezers, raising difficulties of access to the site of implantation.